IκB family consists of a group of proteins that regulate the activity of transcription factor NF-κB by directly binding to NF-κB. The common structural feature of IκBs is the ankyrin repeats that are involved in NF-κB binding. IκBL contains ankyrin repeats and regulates LPS stimulated NF-κB activation. However, it is still unclear whether IκBL can bind to NF-κB directly. Here we reviewed structures and functions of IκB family proteins, and analyzed whether IκBL should be considered as a member of IκB family.